1. Field of the Invention
This invention relates generally to a micro-electro-mechanical system (MEMS) mirror, and more particularly, to a method of adjusting a MEMS mirror control system to implement calibration between the MEMS mirror control system and a particular MEMS mirror.
2. Description of the Prior Art
A MEMS mirror control loop is required to work with MEMS mirrors that may vary significantly in gain (motion for a given current), and resonant frequency. Thirty percent variation from part to part is not uncommon. Such gain and resonant frequency variations are problematic when designing a MEMS mirror control system since a very conservative controller is required to support this wide variance in MEMS mirror gain and resonant frequency. A conservative MEMS mirror controller is undesirable since it will not provide optimum control performance.
In view of the foregoing, it would be both desirable and advantageous in the MEMS mirror art to provide a method of adjusting a MEMS mirror control system to implement calibration between the MEMS mirror control system and a particular MEMS mirror in a fashion that optimizes MEMS mirror control loop performance.
The present invention is directed to a method of calibrating a MEMS mirror control system based on physical parameters of the mirror (gain and resonant frequency) in a fashion that optimizes MEMS mirror control loop performance.
According to one embodiment, a method of calibrating a micro-electro-mechanical (MEM) mirror control system comprises the steps of providing a MEM mirror and a MEM mirror control system having a PID controller comprising proportional, integral, and derivative gain elements, a state estimator element, and a feed-forward control element defined in association with look-up table parameters; measuring the resonant frequency and gain associated with the MEM mirror; and adjusting the PID controller gain elements, the state estimator elements and the feed-forward look-up table parameters as a function of the MEM mirror gain and resonant frequency.
According to another embodiment, a method of calibrating a micro-electro-mechanical (MEM) mirror control system comprises the steps of providing a MEM mirror and a MEM mirror control system having a PID) controller comprising proportional, integral, and derivative gain elements; measuring the resonant frequency and gain associated with the MEM mirror; and adjusting the PID controller gain elements such that each gain element has a desired gain related to the MEM mirror gain and resonant frequency.
According to yet another embodiment, a method of calibrating a micro-electro-mechanical (MEM) mirror control system comprises the steps of providing a MEM mirror and a MEM mirror control system having a state estimator element; measuring the resonant frequency and gain associated with the MEM mirror; and adjusting the state estimator element such that predetermined state estimator parameters are related to the MEM mirror gain and resonant frequency.
According to still another embodiment, a method of calibrating a micro-electro-mechanical (MEM) mirror control system comprises the steps of providing a MEM mirror and a MEM mirror control system comprising a feed-forward control element defined in association with desired look-up table parameters; measuring the resonant frequency and gain associated with the MEM mirror; and scaling the feed-forward look-up table parameters such that the look-up table parameters are related to the MEM mirror gain and resonant frequency.